US4766387A - Motor winding insulation resistance monitoring system - Google Patents

Motor winding insulation resistance monitoring system Download PDF

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Publication number
US4766387A
US4766387A US07/024,813 US2481387A US4766387A US 4766387 A US4766387 A US 4766387A US 2481387 A US2481387 A US 2481387A US 4766387 A US4766387 A US 4766387A
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Prior art keywords
winding
motor
measuring circuit
insulation
signal
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Expired - Lifetime
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US07/024,813
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English (en)
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Frederick D. Browne
Fred E. Sevier
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Charles Stark Draper Laboratory Inc
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Charles Stark Draper Laboratory Inc
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Priority to US07/024,813 priority Critical patent/US4766387A/en
Assigned to CHARLES STARK DRAPER LABORATORY, INC., THE, 555 TECHNOLOGY SQUARE, CAMBRIDGE, MASSACHUSETTS 02139, A MASSACHUSETTS CORP. reassignment CHARLES STARK DRAPER LABORATORY, INC., THE, 555 TECHNOLOGY SQUARE, CAMBRIDGE, MASSACHUSETTS 02139, A MASSACHUSETTS CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: BROWNE, FREDERICK D., SEVIER, FRED E.
Priority to JP33039587A priority patent/JPH0640724B2/ja
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Publication of US4766387A publication Critical patent/US4766387A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34—Testing dynamo-electric machines
    • G01R31/346—Testing of armature or field windings

Definitions

  • This invention relates to a motor winding insulation resistance monitoring system which measures the insulation resistance of a selected motor winding of a polyphase motor while the motor is operating.
  • a major cause of failure in polyphase electric motors is the breakdown of the insulation which protects the motor windings. Such degradation can ruin an expensive motor.
  • insulation failure can cause arcing which burns the plastic insulation and contaminates the refrigerant piping. This may necessitate expensive and time-consuming repairs to the system.
  • a number of devices employ an AC signal to monitor insulation faults.
  • these systems typically require complex electronics and coupling devices.
  • Certain other systems utilize a simpler DC detection circuit.
  • Such systems typically can be used only when the motor is not operating. And in a number of circumstances shutting down a motor can be very undesirable or even wholly unacceptable, such as when it is being employed in a large refrigeration system, such as in a frozen food warehouse, a hospital's water system, a cooling system for a missile or nuclear reactor, or in similar applications where continuous motor operation is essential.
  • Another technique, utilized in refrigerant compressors involves periodically testing the crankcase oil for acidity which can attack the insulation. Again, this technique requires that the compressor be shut down and also requires extensive operator intervention to open and close valves, take oil samples and check for leaks.
  • One device does employ DC detection to monitor insulation faults while the motor remains operational. However, it operates only with an ungrounded electrical power source and inasmuch as most power sources are grounded, this device has limited application. It also shuts down the motor which as indicated above may be very undesirable.
  • This invention results from the realization that the motor winding insulation resistance of a polyphase motor may be effectively and simply monitored while the motor remains operating by selectively disconnecting each winding from its respective phased power source and reconnecting that winding with an insulation measuring circuit which applies a test voltage to the winding so that the leakage resistance can be measured while the remaining windings continue to operate the motor.
  • This invention features a motor winding insulation resistance monitoring system for measuring the insulation resistance of a winding of a polyphase motor while the motor is operating.
  • the system includes a winding insulation resistance measuring circuit and switching means for selectively interconnecting each winding with a separate phased power source and the insulation resistance measuring circuit. There are means for directing the switching means to disconnect a winding from its power source and connect one end of that winding with the motor winding insulation measuring circuit to measure the resistance of that winding's insulation to ground while the motor continues operating.
  • the motor winding insulation measuring circuit includes means for applying a test voltage to the winding which is disconnected from its power source.
  • the means for applying may include means for applying a DC test voltage to the disconnnected winding.
  • the measuring circuit may be connected to an AC signal source and the means for applying may include means for filtering the AC signal from the circuit.
  • the means for applying may include a voltage doubler attached to an AC signal source for converting the AC signal to DC, doubling the signal and providing the doubled DC signal to the disconnected winding.
  • the measurement circuit may include means for limiting current through the voltage doubler.
  • the measurement circuit may also include means, responsive to the applied test signal, for developing a signal which is indicative of the disconnected winding's insulation resistance.
  • the means for developing may include means for filtering AC signals provided to the measuring circuit by the windings which remain connected.
  • the measuring circuit may also include means responsive to the developed signal for determining the winding insulation resistance.
  • the switching means may include a double pole, double throw switch associated with each winding.
  • the switching means may include relay means connected to a source of power and the means for directing may include means for selectively energizing the relay means to interconnect an associated winding with one of its phased power source and the insulation measuring circuit and de-energizing the relay means to interconnect the winding with the other of its phased power source and the winding insulation measuring circuit.
  • the means for selectively energizing and de-energizing may include a manually operable switch, timer means and/or microprocessor means. Preferably there are means for interconnecting only one motor winding at a time with the measuring circuit. Means responsive to the measuring circuit may be provided for indicating the measured insulation resistance.
  • FIG. 1 is a block diagram of a motor winding insulation resistance monitoring system for a polyphase motor according to this invention
  • FIG. 2 is a schematic view of a preferred circuit for implementing the monitoring system
  • FIG. 3 is an front elevational view of a push button device for selecting the winding to be monitored by the monitoring system
  • FIG. 4 is a schematic view of an alternative rotary switch for selecting the winding to be monitored.
  • FIG. 5 is a schematic view of an alternative means such as a timer or a microprocessor for selecting the winding to be monitored.
  • the motor winding insulation resistance monitoring system of this invention measures the insulation resistance of a winding of a polyphase motor while the motor remains operating.
  • the windings are mounted on the stator.
  • the windings may be provided on the rotor of the polyphase motor.
  • the system includes a winding insulation measuring circuit and switching means such as a double pole double throw switch for selectively interconnecting each winding with a different phased power source and the insulation resistance measuring circuit.
  • solid-state winding isolation switches or various other switching means may be employed. These switches are restricted to interconnecting only one winding at a time with the measuring circuit.
  • the switches include a number of relay mechanisms which are connected to a source of power and selectively energized to interconnect respective windings with either the phased power source or the insulation measuring circuit. When a relay is de-energized, the winding is connected with the other of the phased power source and the insulation measuring circuit.
  • These relays may be energized and de-energized in a number of ways. For example, each may be operated by a manually operable pushbutton switch. A slide mechanism or other device may be provided so that only one switch at a time may be pushed. Alternatively, a rotary switch may be utilized. A timer may be employed to energize and de-energize the relay means at predetermined intervals and such control may also be provided by a microprocessor, for example, the Hewlett-Packard 3488A switch control unit.
  • the measuring circuit preferably operates by applying a DC test voltage to the armature winding of interest.
  • line AC voltage is provided to a voltage doubler which converts the AC signal to DC, doubles the signal and provides that doubled signal to the disconnected winding.
  • a preferred voltage doubler (multiplier) is Part No. 5VMS10, manufactured by Murata Erie.
  • a resistor or similar means may be provided for limiting the current through the voltage doubler in the event of a short circuit.
  • a leakage current Due to the test voltage, a leakage current, the level of which is dependent upon the degree of degradation of the winding's insulation, flows from the winding to the frame of the motor. This leakage current is directed back through the measuring circuit which develops a signal indicative of the disconnected winding's insulation resistance. The signal is typically developed across a resistor. This signal may then be processed to determine the insulation resistance of the winding.
  • a digital or analog display may be provided to indicate the detected resistance or alternatively the leakage current or resistance signal.
  • a strip chart recorder, printer or other recording device may be utilized to provide a record of these measurements. Various types of alarms may also be employed to warn of an undesirably low or undesirably high resistance. And corrective action electronics may be utilized to disconnect the load or power or perform other required action when defective conditions are sensed.
  • the normal operating resistance of a winding's insulation is typically between 100 megaohms and 100,000 megaohms and this system can measure deviations from that range.
  • the invention is particularly effective for detecting insulation resistance which has dropped below 20 megaohms, the level at which problems with the insulation typically commence.
  • the system can also be used to indicate when an undesirably large insulation resistance is present, for example, due to excessive drying and moisture loss from the insulation.
  • a selected one of the windings is monitored in the above manner while the remaining two windings continue to operate the motor.
  • the measurement interval for such an embodiment is preferably only as long as required for the reading to stabilize, e.g., approximately one-half minute. This interval is brief enough that the motor may be operated by the two remaining windings.
  • FIG. 1 a motor winding insulation resistance monitoring system 10 for measuring the insulation resistance of windings 12, 14 and 16 of polyphase induction motor 18.
  • phase isolation switch mechanism 20 connects three phase line power over lines L1, L2 and L3 to respective windings 12, 14 and 16.
  • switch control device 25 operates switch mechanism 20 to selectively disconnect winding 12 from phased power line L1 and reconnect it with a test voltage signal 28 from resistance measuring circuit 30.
  • Circuit 30 is itself powered by voltage line L1.
  • the test voltage applied across winding 12 causes current to leak from winding 12 through the defective insulation to frame 32 of motor 18.
  • This leakage current is returned over line 34 to resistance measuring circuit 30 which derives a signal from the current.
  • This signal is then used to determine the insulation resistance and a signal R which is representative of that resistance is transmitted to and indicated by display 36.
  • switch mechanism 20 includes three double pole, double throw switches 37, 38 and 39 which are associated with windings 12, 14 and 16 respectively.
  • Each switch includes a pair of switchable contacts 40 and 41 and a relay coil 42.
  • contact 40 of switch 37 engages fixed contact 53 of phased power line L1 and contact 41 engages contact 56 of neutral line N1. This completes a circuit from the phased power line through winding 12 and to the neutral line.
  • Windings 14 and 16 are similarly provided with power from lines L2 and L3 through switches 38 and 39.
  • Each relay coil 42 is connected respectively at one end to power line L1.
  • the opposite end of each relay coil is selectively connected to neutral line N1 through a respective pushbutton switch 50, 52 and 54 within switch control device 25. While switches 50, 52 and 54 are open their respective relay coils 42 remain de-energized. As a result, the contacts 40 and 41 of each switch 37, 38 and 39 remain engaged with fixed contacts 53 and 56, respectively.
  • an associated relay coil 42 is energized by power from line L1 to operate one of the switches 37, 38 or 39 of mechanism 20 so that it disconnects its associate winding from phased power line L1, L2 or L3 and reconnects it with measuring circuit 30. The details of this operation are described more fully below.
  • Resistance measuring circuit 30, FIG. 2 includes a voltage doubler 63 which is connected to power from phased power line L1.
  • An output line 62 extends from the positive terminal of voltage doubler 60 across limiting resistor 64 and terminates at contacts 81 within respective switches 37, 38 and 39 of switch mechanism 20.
  • a neutral line N2 connected to frame 32 of motor 18 returns to circuit 30.
  • a 6200 ohm resistor 66 and a bypass capacitor 67 are connected across line N2 and line 68 which returns to the negative terminal of voltage doubler 60.
  • a signal processor 70 is connected across lines N2 and 68. The output of the signal processor drives various devices of display 36.
  • Such display devices may include, for example, a digital display 74, a strip chart recorder 76, and an alarm 78 which may signal when either the resistance is too low or too high.
  • Voltage doubler 60 converts the AC signal it receives from line L1 to DC and doubles the voltage received from the power line to provide an output of approximately 250 volts over line 63.
  • Limiting resistor 64 protects the voltage doubler from damage in case of a short circuit. This voltage is applied through terminal 81 and contact 41 to winding 12. As a result, current leaks through the winding's insulation, as indicated by resistance 82, to ground, e.g., to frame 32 of motor 18. The degree of leakage is dependent upon the condition of the insulation and hence the resistance provided by the insulation. If the insulation is in good condition, leakage should be relatively small. However, worn or degraded insulation will result in an increased leakage current to the motor frame.
  • the leakage current is conducted by line N2 back to measurement circuit 30.
  • resistor 66 develops a signal S which is representative of the resistance of the winding's insulation.
  • this signal may include an undesirable AC component resulting from capacitive coupling between the winding being measured and the two remaining windings which continue to employ an AC signal to drive the motor.
  • This AC component constitutes noise which can interfere with the resistance measurement.
  • capacitor 67 is provided to reduce the effects of capacitive coupling by filtering the AC component from signal S. Filtered signal S is then provided to a signal processor 70 which calculates the insulation resistance according to the following formula:
  • R is the insulation resistance
  • V A is the applied test voltage
  • I L is the leakage current
  • the leakage current I L is itself determined according to the formula:
  • a signal representative of the detected measured insulation resistance is thus provided, for example, to digital display 74, recorder 76 and alarm 78.
  • Pushbutton switches 50, 52 and 54, FIG. 3, are located on the front face of a housing 100 which contains system 10.
  • the measuring circuit located within housing 100, is turned on by actuating switch 67 and an individual winding is then monitored by depressing a selected one of the pushbutton switches 50, 52 and 54.
  • slide 120 is disposed between the rearward end of the respective pushbutton switches 50, 52 and 54 and neutral line N2. Slide 120 is attached by an elongated element, not shown, to an adjusting lever 122 located outside of housing 100.
  • Lever 122 is generally aligned with a notch 124 in slide 120.
  • the notch permits a selected pushbutton to pass therethrough and engage the neutral line when that pushbutton switch is depressed.
  • notch 124 is positioned to receive pushbutton switch 52 so that winding 14, FIG. 2, can be monitored by the resistance measuring circuit. And the measured insulation resistance is indicated on digital display 74.
  • slide 120 prevents buttons 50 and 54 from being depressed. Windings 12 and 16 therefore remain energized to operate the motor.
  • lever 122 In order to engage pushbutton switch 50 and thereby monitor its associated winding 12, lever 122 is moved in the direction of arrow 126 until notch 124 is positioned to receive pushbutton switch 50. This provides switch 50 with access to the neutral wire so that its associated winding 12 can be monitored by the resistance measuring circuit. At the same time, slide 120 prevents depression of pushbutton switches 52 and 54. To monitor winding 16, switch 54 is actuated in a manner identical to switches 50 and 52. When measurements are no longer required the measuring circuit is turned off by actuating "off" button 69.
  • each of the pushbutton switches 50, 52 and 54 must be depressed against a heavy spring which urges the pushbutton into a raised condition so that its associated relay coil is de-energized. This discourages the operator from disconnecting one of the windings for an undesirably long period of time.
  • FIG. 4 An alternative mechanism for energizing and de-energizing relay coils 42a, 42b and 42c (each associated with one of the windings of the motor) is shown in FIG. 4.
  • Each of the coils is connected at one end to a phased power line L4.
  • the opposite end of each coil includes a respective terminal 110, 112 and 114.
  • a rotary switch 116 is connected to a neutral line N3 and is biased by a spiral spring 118 so that it does not engage terminals 110, 112 and 114.
  • coils 42a, 42b and 42c remain de-energized and their associated windings remain energized to operate the motor.
  • relay coils 42a, 42b and 42c To selectively disconnect those windings for measuring their insulation resistance, relay coils 42a, 42b and 42c must be selectively energized. This is accomplished by rotating switch 116 in a clockwise direction so that it engages one of terminals 110, 112 and 114. When one of the terminals is engaged its associated relay coil is energized and as a result its associated winding is de-energized so that its insulation resistance may be measured. When testing is completed the rotary switch is released and spring 118 urges it back into its initial condition spaced apart from each of the terminals. As shown in phantom, switch 116 can engage only one terminal at any one time. As a result, at least two of relay coils 42a, 42b,and 42c always remain de-energized and their two associated motor windings are energized to drive the motor even while one of the windings is being measured.
  • each of relay coils 42d, 42e and 42f is attached at one end to a power line L5.
  • the other end of each coil is attached to a timer 150.
  • the timer selectively connects the opposite end of each relay coil with a neutral line N4 so that one coil at a time may be energized.
  • a microprocessor 160 may be programmed to selectively actuate coils 42d, 42e and 42f and thereby disconnect one armature winding at a time for insulation resistance testing as described above.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Tests Of Circuit Breakers, Generators, And Electric Motors (AREA)
  • Induction Machinery (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
US07/024,813 1987-03-12 1987-03-12 Motor winding insulation resistance monitoring system Expired - Lifetime US4766387A (en)

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US07/024,813 US4766387A (en) 1987-03-12 1987-03-12 Motor winding insulation resistance monitoring system
JP33039587A JPH0640724B2 (ja) 1987-03-12 1987-12-28 電動機巻線絶縁抵抗監視装置

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Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5243243A (en) * 1991-11-12 1993-09-07 Andrews J Leroy Electric motor insulation resistance fault monitor
US5307019A (en) * 1992-09-21 1994-04-26 Slaughter Company, Division Of R. E. Phelon Company, Inc. Method and apparatus for determining the weld and coil resistances of a motor winding
US5428282A (en) * 1993-01-08 1995-06-27 Fluidmaster, Inc. Release-type permanent magnet motor
US5510726A (en) * 1993-11-17 1996-04-23 R. E. Phelon Co., Inc. Armature tester
US5550477A (en) * 1994-08-01 1996-08-27 Axis Usa, Inc. Methods and apparatus for testing armature coils and coil lead connections using resistance measurements
US5612601A (en) * 1993-11-22 1997-03-18 Martin Marietta Energy Systems, Inc. Method for assessing motor insulation on operating motors
US5644242A (en) * 1995-06-21 1997-07-01 Fisher; James Allan Armature winding and winding connection test methods
WO1999026076A1 (en) * 1997-11-18 1999-05-27 Emerson Electric Co. Apparatus for and method of monitoring the status of the insulation on the wire in a winding
US6093988A (en) * 1997-11-06 2000-07-25 Kabushiki Kaisha Meidensha Rotating electric machine usable in radioactive environment
US6133661A (en) * 1997-11-06 2000-10-17 Kabushiki Kaisha Meidensha Rotating electric machine usable in radioactive environment
US6621291B2 (en) * 2001-08-15 2003-09-16 Eaton Corporation Device and method for estimating the resistance of a stator winding for an AC induction motor
US20030178999A1 (en) * 2002-03-19 2003-09-25 Emerson Electric Co. Method and system for monitoring winding insulation resistance
US20030234653A1 (en) * 2002-02-06 2003-12-25 Ballard Power Systems Ag Method and device for insulation monitoring of a DC network
KR100497515B1 (ko) * 2002-03-14 2005-07-01 디이시스 주식회사 전동기의 절연감시 장치
US20050151658A1 (en) * 2004-01-13 2005-07-14 Fanuc Ltd Motor Driver
US20050226308A1 (en) * 2004-04-13 2005-10-13 Hudson Jeffrey A Temperature detection method and apparatus for inverter-driven machines
US20080150549A1 (en) * 2006-12-21 2008-06-26 Fanuc Ltd Insulation deterioration detection device for motor
US20090251154A1 (en) * 2008-04-02 2009-10-08 Caterpillar Inc. System and method for testing winding insulation resistance
FR2989778A1 (fr) * 2012-04-23 2013-10-25 Renault Sa Procede de determination de la localisation de defauts d'isolation electrique dans un bobinage de moteur electrique.
US20140071563A1 (en) * 2012-09-10 2014-03-13 Dean Solon Monitoring system for and method of preventing electrical arcs in a solar energy system
US20150301093A1 (en) * 2012-11-20 2015-10-22 Phoenix Contact Gmbh & Co. Kg Functional unit for measuring the insulation resistance of an electrical system
CN105150855A (zh) * 2011-03-07 2015-12-16 Ntn株式会社 电动汽车用驱动电动机的诊断装置
US9255970B2 (en) 2012-09-27 2016-02-09 General Electric Company On-line monitoring of stator insulation in motors and generators
CN110703097A (zh) * 2019-11-05 2020-01-17 合肥致臻电子科技有限公司 一种风力发电机绝缘电阻在线监控仪和监测方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4199559B2 (ja) * 2003-02-19 2008-12-17 株式会社アピステ 三相誘導モータ絶縁劣化監視装置

Citations (3)

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Publication number Priority date Publication date Assignee Title
SU48105A1 (ru) * 1935-11-26 1936-08-31 Е.Г. Свердлов Штамп дл изготовлени карабинов из проволоки
US2525413A (en) * 1946-11-07 1950-10-10 Westinghouse Electric Corp Testing apparatus for generator winding insulation
US2759145A (en) * 1952-03-24 1956-08-14 Everett R Manley Apparatus for testing motor windings

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU48105A1 (ru) * 1935-11-26 1936-08-31 Е.Г. Свердлов Штамп дл изготовлени карабинов из проволоки
US2525413A (en) * 1946-11-07 1950-10-10 Westinghouse Electric Corp Testing apparatus for generator winding insulation
US2759145A (en) * 1952-03-24 1956-08-14 Everett R Manley Apparatus for testing motor windings

Cited By (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5243243A (en) * 1991-11-12 1993-09-07 Andrews J Leroy Electric motor insulation resistance fault monitor
US5307019A (en) * 1992-09-21 1994-04-26 Slaughter Company, Division Of R. E. Phelon Company, Inc. Method and apparatus for determining the weld and coil resistances of a motor winding
US5428282A (en) * 1993-01-08 1995-06-27 Fluidmaster, Inc. Release-type permanent magnet motor
US5510726A (en) * 1993-11-17 1996-04-23 R. E. Phelon Co., Inc. Armature tester
US5612601A (en) * 1993-11-22 1997-03-18 Martin Marietta Energy Systems, Inc. Method for assessing motor insulation on operating motors
US5550477A (en) * 1994-08-01 1996-08-27 Axis Usa, Inc. Methods and apparatus for testing armature coils and coil lead connections using resistance measurements
US5644242A (en) * 1995-06-21 1997-07-01 Fisher; James Allan Armature winding and winding connection test methods
US6093988A (en) * 1997-11-06 2000-07-25 Kabushiki Kaisha Meidensha Rotating electric machine usable in radioactive environment
US6133661A (en) * 1997-11-06 2000-10-17 Kabushiki Kaisha Meidensha Rotating electric machine usable in radioactive environment
WO1999026076A1 (en) * 1997-11-18 1999-05-27 Emerson Electric Co. Apparatus for and method of monitoring the status of the insulation on the wire in a winding
US6087836A (en) * 1997-11-18 2000-07-11 Emerson Electric Co. Apparatus for and method of monitoring the status of the insulation on the wire in a winding
US6392419B1 (en) 1997-11-18 2002-05-21 Emerson Electric Co. Apparatus for and method of monitoring the status of the insulation on the wire in a winding
US6621291B2 (en) * 2001-08-15 2003-09-16 Eaton Corporation Device and method for estimating the resistance of a stator winding for an AC induction motor
US20030234653A1 (en) * 2002-02-06 2003-12-25 Ballard Power Systems Ag Method and device for insulation monitoring of a DC network
US6879164B2 (en) * 2002-02-09 2005-04-12 Ballard Power Systems Ag Method and device for insulation monitoring of a DC network
KR100497515B1 (ko) * 2002-03-14 2005-07-01 디이시스 주식회사 전동기의 절연감시 장치
US6794883B2 (en) * 2002-03-19 2004-09-21 Emerson Electric Co. Method and system for monitoring winding insulation resistance
US20030178999A1 (en) * 2002-03-19 2003-09-25 Emerson Electric Co. Method and system for monitoring winding insulation resistance
US20050151658A1 (en) * 2004-01-13 2005-07-14 Fanuc Ltd Motor Driver
US7256701B2 (en) * 2004-01-13 2007-08-14 Fanuc Ltd Motor driver
US20050226308A1 (en) * 2004-04-13 2005-10-13 Hudson Jeffrey A Temperature detection method and apparatus for inverter-driven machines
US7111983B2 (en) * 2004-04-13 2006-09-26 Reliance Electric Technologies, Llc Temperature detection method and apparatus for inverter-driven machines
US20070019706A1 (en) * 2004-04-13 2007-01-25 Hudson Jeffrey A Temperature detection method and apparatus
US20080150549A1 (en) * 2006-12-21 2008-06-26 Fanuc Ltd Insulation deterioration detection device for motor
US20090251154A1 (en) * 2008-04-02 2009-10-08 Caterpillar Inc. System and method for testing winding insulation resistance
US8093906B2 (en) 2008-04-02 2012-01-10 Caterpillar, Inc. System and method for testing winding insulation resistance
CN105150855A (zh) * 2011-03-07 2015-12-16 Ntn株式会社 电动汽车用驱动电动机的诊断装置
CN105150855B (zh) * 2011-03-07 2017-08-08 Ntn株式会社 电动汽车用驱动电动机的诊断装置
FR2989778A1 (fr) * 2012-04-23 2013-10-25 Renault Sa Procede de determination de la localisation de defauts d'isolation electrique dans un bobinage de moteur electrique.
US20140071563A1 (en) * 2012-09-10 2014-03-13 Dean Solon Monitoring system for and method of preventing electrical arcs in a solar energy system
US9255970B2 (en) 2012-09-27 2016-02-09 General Electric Company On-line monitoring of stator insulation in motors and generators
US20150301093A1 (en) * 2012-11-20 2015-10-22 Phoenix Contact Gmbh & Co. Kg Functional unit for measuring the insulation resistance of an electrical system
CN110703097A (zh) * 2019-11-05 2020-01-17 合肥致臻电子科技有限公司 一种风力发电机绝缘电阻在线监控仪和监测方法

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Publication number Publication date
JPS63224650A (ja) 1988-09-19
JPH0640724B2 (ja) 1994-05-25

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